Health Imaging & IT - December 2008 - (Page 25)

state detector columns, cadmium zinc telluride (CZT) crystals, wide-angle tungsten collimators, region of interest-centric scanning, and increased angular sampling, has shown remarkable benefit for myocardial perfusion imaging (MPI). According to an international team of researchers from Israel, London and CedarsSinai Medical Center in Los Angeles, the technology has recently been shown to provide an 8- to 10-fold increase in sensitivity, coupled with a two-fold improvement in spatial resolution, and has enabled a significant reduction in imaging time and dose of radioisotopes (JACC: CI, March 2008). Their pilot study demonstrated that highspeed SPECT studies with 4-minutes of stress and 2-minutes of rest acquisition resulted in high-quality images, perfusion abnormality highly correlated to conventional SPECT, and an equivalent level of diagnostic confidence. The commercial launch of SPECT/CT systems by Philips Healthcare, GE Healthcare and Siemens Healthcare over the past decade has played a strong role in the growing utilization of SPECT for CAD imaging. These hybrid modalities have allowed the direct fusion of morphologic and functional information for physicians, providing even greater clinical clarity and better patient management. Jean Luc Urbain, MD, PhD, chief and chair of nuclear medicine at the University of Western Ontario, Schulich School of Medicine and Dentistry in London, Ontario, says the facility began its SPECT/CT program with a GE Hawkeye in 2004 and immediately saw utilization of the modality proliferate. “We now have four units installed, and a fifth one coming on-line shortly,” he says. His practice does quite a bit of nuclear cardiac studies on the units, as many oncology exams as it can, and a fair amount of musculoskeletal imaging. “We see 3,000 patients for stress tests with MPI a year, mostly on SPECT/CT,” he says. “Cardiology represents about 40 percent of our business annually, oncoloHealthImaging.com [ This low-dose scan (2.1 mSv) of a 47-year-old female with chest pain was taken using Step & Shoot on the Philips Healthcare Brilliance CT system. The scan was performed to rule out CAD. Findings show a significant narrowing of the mid-LAD, consistent with myocardial bridging and normal RCA. ] gy about 30 to 40 percent, and the rest is musculoskeletal.” The department bases its determination of SPECT/CT exam usage on whether the SPECT portion of the study will be enhanced by CT capabilities, Urbain says. “My estimate is about 35 percent of the time SPECT images are enhanced by the CT portion of equipment.” One of the greatest advantages to using SPECT/CT is that the specificity of the diagnoses from the department has been greatly enhanced, Urbain says. “Now that we have the capability to view the functional and anatomic aspects of the exam together, we are very confident about the localization of what we see. Overall, it has improved tremendously our ability to diagnose accurately.” This has been most evident in the practice’s MPI studies. Urbain says that they’ve been able to decrease uncertainty in these exams by about 20 to 25 percent by conducting the procedures on SPECT/CT, which has led to better patient management. “It has drastically improved our ability to diagnose, or rule out, ischemia,” he notes. SPECT/CT has provided another benefit to the facility; by its capability to increase diagnostic certainty, physicians are now better able to provide a diagnosis without conducting additional imaging studies on other modalities. This, in turn, has allowed greater utilization of these technologies for other patients. Urbain is particularly excited about the possibilities for the future of SPECT/CT in cardiac imaging. He and his colleagues have begun an investigation into the efficacy of SPECT/CT MPI procedures being conducted with coronary CT angiography (CTA) in a single patient session. “We have learned so much over the past six months that we can probably began rewriting textbooks,” he says. “We are seeing things that we never would have suspected.” Given the capability to design an ideal SPECT/CT system, Urbain would opt for a cardiac dream machine. “From the medical/scientific aspect, I’d like to see a CZT SPECT paired with at least a 64-slice CT in order to do cardiac work,” he says. Further south, David Davidson, a certified nuclear medicine technologist (CNMT) and clinical coordinator of the nuclear medicine department at the Medical University of South Carolina (MUSC) in Charleston reported that his facility also has experienced a significant increase in cardiac presentations for molecular imaging. So much so that MUSC has dedicated its recently acquired Siemens Symbia TruePoint SPECT/CT systems (one T2 and two T6 models) for deployment at a newly constructed cardiology and digestive diseases hospital. “We’re performing a lot of myocardial perfusion imaging using Cardiolite [Lantheus Medical Imaging] technetium Tc99m sestamibi,” Davidson says. “Now that we’ve opened up our new facility, we’re really concentrating on our SPECT/CT cardiac imaging.” He notes that clinicians at the facility have found tremendous benefit to the attenuation correction available with the CT portion of the hybrid technology. “There are different ways of performing attenuation correction for cardiac studies,” he says. “One is with a sealed source, which is not quite as good as doing it with a CT. The CT portion of the SPECT/CT has better imaging characteristics and is not as limiting as the sealed-source method. In addition, sealed sources have to be replaced every 12 to 18 months due to their half-life, which poses an additional problem. It also just doesn’t have the strength of CT alone for the morbidly obese patient. We feel that the CT method for attenuation correction combined with SPECT is far superior to what we’ve used in the past.” December 2008 | Health Imaging & IT 25 http://www.HealthImaging.com

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Health Imaging & IT - December 2008 Table of Contents The Enterprise News Update Technology at Work: What You Need to Compete Why 1.5T MRI is Leading the Pack Workflow Strategies Aid Advanced Visualization Deployment Illuminating Reading Room Design for Better Reading Strategies Cardiac SPECT Sharpens its Focus OrthoPACS: The Information Backbone of the Orthopedic Clinic Imaging Tools Reader's Resource

Health Imaging & IT - December 2008

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